lactam Chem.
(ˈlæktæm)
[a. G. lactam (Baeyer & Oekonomides 1882, in Ber. d. Deut. Chem. Ges. XV. 2102), f. lact-on lactone + am-id amide.]
Any of the class of cyclic amides analogous to the lactones, characterized by the group {b1}NH·CO{b1} as part of a ring (lactam ring) and formed by the elimination of a molecule of water from an amino and a carboxyl group of an acid; freq. with prefixed Gr. letter (see lactone 2).
| 1883 Jrnl. Chem. Soc. XLIV. 202 The authors propose the name lactam for bodies formed like acetylisatin, and lactim for those formed like isatin. 1910 Encycl. Brit. VI. 59/1 The internal anhydrides of aminocarboxylic acids (lactams, betaines). 1936 L. J. Desha Org. Chem. xxvi. 522 Lactam-lactim tautomerism involves the shift of a hydrogen atom from nitrogen to oxygen and vice versa. 1949 E. P. Abraham et al. in H. W. Florey et al. Antibiotics II. xv. 669 The four-membered lactam ring which was present in this structure [of penicillin] had not previously been found in natural compounds, and the ease with which it could be broken was responsible for the instability of penicillin under a variety of conditions. 1964 Roberts & Caserio Basic Princ. Org. Chem. xx. 712 Formation of α- and β-lactams is expected to generate considerable ring strain, and other more favorable reactions usually intervene. 1966 McGraw-Hill Encycl. Sci. & Technol. VII. 377/1 Although γ- and δ-amino acids are nontoxic themselves, the corresponding lactams show pronounced strychnine-type toxicity. |